This invention relates to tube-in-shell heat exchangers and is directed towards intermediate heat exchangers for use in liquid metal cooled fast breeder nuclear reactor constructions.
A tube-in-shell heat exchanger comprises a closed shell housing a bundle of heat exchange tubes which pass through the shell by way of a transverse tube sheet or sheets. In use a first fluid flows through the shell in heat exchange with a second fluid flowing through the tubes. In one kind of tube-in-shell heat exchanger used as an intermediate heat exchanger in a liquid metal cooled fast breeder nuclear reactor constructions, the tubes being elongate and extending between opposed tubes sheets incorporate expansion bends and therefore are subject to severe vibration due to fluid flow through the shell. One expedient to prevent vibrational movement is to support the tubes transversely by a series of longitudinally spaced grids of which successive grids radially displace the tubes from their nominal in-line positions in opposed directions in order to strain the tubes. However, tube support provided by this expedient can be too rigid, and the differential movement of the tubes relative to the other parts of the structure thereby induces severe stress.